Some people pronounce nvidia as nuhvidia others as envidia so when the writer puts "a" or "an" before it they're revealing how they pronounce it

I avoid making exceptions to the rule, but in the vernacular, people definitely break from it! You'll see e.g. "an historic event", usually justified because the first syllable is weak and close enough to being vowel-started.

FWIW "an Nvida employee" sounds better than me an "a Nvidia employee" because the latter has two vowels with no consonant separating them ... and I don't get repetition there because the vowels are different.